A large number of exercising machines have been conceived and patented, and may be classified generally into passive and active types. In the passive types of exercising apparatus, an electric motor moves the legs and/or arms (limbs) of the exerciser. In the active types, motive power is supplied by the exerciser, who works against various loads.
Despite the large number of types of apparatus which have been devised and used over many decades, there remains a major need for a method and apparatus which provide active and passive exercising, which can be transitioned from any desired degree of active exercising to any desired degree of passive exercising without stopping the machine, which can be used with maximum safety at various degrees of incline ranging from the horizontal to quite steep, which has stride-length adjustments that can be effected while the apparatus is in motion, and which is characterized by harmonic motion and by the absence of jerks or jolts even if the motor is suddenly turned off. It is highly desirable that the machine be self-contained so as to be readily movable to any location. The mechanism for achieving any degree of inclination must be simple yet rugged and effective.